...

Core 10 and 11 were isolated from the OS using the isolcpus argument to grub command line and using virsh to Pin the vCPUs to those cores (Requires KVM acceleration):

$ virsh vcpupin test 0 10
$ virsh vcpupin test 1 11

To check for KVM acceleration see that the response to the command below is > 0:

$ cat /proc/cpuinfo | egrep -c '(vmx|svm)'

without KVM acceleration you will need to taskset the qemu threads to the isolated cores:

$ grep pid /var/run/libvirt/qemu/test.xml
<domstatus state='running' pid='4907'>
$ grep Cpus_allowed_list /proc/4907/task/*/status
/proc/4907/task/4916/status:Cpus_allowed_list: 4
/proc/4907/task/4917/status:Cpus_allowed_list: 5
/proc/4907/task/4918/status:Cpus_allowed_list: 6
/proc/4907/task/4919/status:Cpus_allowed_list: 7
</section>

To taskset the process + tasks repeat the following for the PID and the subtasks:

$ taskset -pc 4 4907...

Guest

OS: Ubuntu 16.04.2 LTS

Install collectd and stress

$ sudo apt install collectd stress stress-ng

configure /etc/collectd/collectd.conf

Hostname "ubuntu_vm"

<LoadPlugin cpu>
  Interval 1
</LoadPlugin>

LoadPlugin network
 
<Plugin cpu>
        ReportByCpu true
        ReportByState false
        ValuesPercentage false
</Plugin>

<Plugin network>
#       # client setup:
        Server "<HOST IP>" "28597"
        <Server "<HOST IP>" "28597">
        </Server>
</Plugin> 

Start collectd on the host and the guest

$ service collectd start

Run Stress in the VM on a single core

$ taskset 1 stress -c 2 -t 10
stress: info: [1422] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
stress: info: [1422] successful run completed in 10s